<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    select{
      width: 100px;
      height: 100px;
    }
  </style>
</head>
<body>
  <select id="left" multiple>
    <option value="">1</option>
    <option value="">2</option>
    <option value="">3</option>
    <option value="">4</option>
    <option value="">5</option>
    <option value="">6</option>
    <option value="">7</option>
    <option value="">8</option>
    <option value="">9</option>
  </select>
  <button onclick="append(left,right)">></button>
  <button onclick="append(right,left)"><</button>
  <select id="right" multiple></select>

  <script>
    function append(left,right){
      var options = left.childNodes;
      for(var i=options.length-1;i>=0;i--){
        if(options[i].nodeType !== 1) continue;
        if(options[i].selected){
          options[i].selected = false;
          //添加到开头
          right.insertBefore(options[i], right.firstChild);
        }
      }
    }
  </script>
</body>
</html>